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82571EB/82572EI EEPROM Information Guide
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1.11
ASF Controller Words
When the 82571EB/82572EI is in ASF mode, its ASF function reads the ASF section from the
EEPROM. For the 82571EB/82572EI, this section is in words 40h through F7h. These words are
read after power up (LAN_PWR_GOOD assertion), ASF Soft Reset (ASF FRC_RST), or software
commanded ASF EEPROM read (ASF FRC_EELD).
Note:
These words should be programmed by ASF configuration software. The value of the words from
the factory should be all FFh.
1.11.1
ASF Words - Content
The interpretation of these words depends on the ASF Mode functionality.
1.11.2
ASF Words - EEPROM Checksum (CRC)
While reading the ASF EEPROM words, the 82571EB/82572EI computes the ASF CRC word.
Words 40h:F7h are included in the CRC calculation and compared against the CRC value present
in word F7h. If the CRC values mismatch, the 82571EB/82572EI does not overwrite the ASF
Configuration Registers with the EEPROM values. Therefore, if the ASF CRC is bad, hardware
default values are initially present in ASF registers and any subsequent re-read of the EEPROM
leaves the ASF registers unchanged (from values current at the time of the EEPROM read).
The details of this CRC can be found at:
http://cell-relay.indiana.edu/cell-relay/publications/software/CRC/32bitCRC.tutorial.html.